1. Overproduction of the cystic fibrosis protein. It is possible that the 
gene therapy will cause too much CFTR to be made in the airway 
cells. Animal research has suggested that this is not going to be a 
hazard in humans. Tests in animals have shown that increasing the 
amount of CFTR protein made by many times does not cause any 
problems. Whether this is true in humans is not known. 
2. Multiplication of the virus. The virus that I will receive into my 
airways is being modified so that it cannot reproduce itself. It is 
possible that something will alter the virus in my body so that it 
becomes infectious again. It is thought by the doctors that this is a 
very remote possibility, but the effects of this happening are 
unknown. If the virus were to become infectious, my body would 
probably start to kill the virus after a short time, just as when 
people have colds. 
3. Damage to the airway cells. The virus could injure the cells in my 
nose and lower airways. The research performed so far with animal 
and human cells in the laboratory have not shown that this happens. 
However, if the airway cells were damaged, it is possible that the 
lining of my nose, or the lobe that is treated, could be damaged by 
the virus either temporarily or permanently. 
4. Environmental spread of the virus. It is possible that the virus will 
become infectious and leave my body and spread into the 
environment. However, the virus has been modified in the lab so 
that this should not occur. The adenovirus probably would not 
behave any differently to other types of adenovirus that are already 
preseht in the environment. If my body continues to excrete the 
virus at the end of the study, I will be asked to stay in the hospital 
until my cultures become negative. 
5. Malignancy. The cold virus being used in these studies is not one 
which causes cancer. Other types of virus can damage normal genes 
when they insert into the chromosomes. Because the adenovirus 
does not usually insert into genes on the chromosomes, it is very 
unlikely that the virus could cause cancer. 
6. Modification of the sperm or eggs. If the virus spread through my 
body, it is possible that the cystic fibrosis gene could be inserted into 
the body's eggs or sperm. I have been informed by the doctors that 
I can only participate in the study if I am sterile, to avoid the chance 
that I could pass genetic changes in my body's eggs or sperm to 
children. It is thought by the doctors that this is a very remote 
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